Oil-lubricated rotary vane vacuum pump

ABSTRACT

An oil-lubricated rotary vane vacuum pump has a rotary vane unit that includes a rotary vane chamber and a rotary vane rotor. The vacuum pump has an oil separation and reprocessing device in which oil and gas that have penetrated into the rotary vane unit are separated by a separation device formed by a filter element and/or a gravitational and/or impact separator and/or a fine particle separator, preferably along with an oil foam decomposition device and/or with an oil cooler and/or with an oil pump. One or more monitoring and/or maintenance devices are provided for the devices, and the oil separation and reprocessing device is accommodated in an oil separation and reprocessing housing. The gas successively flows through two separation devices within the oil separation and reprocessing housing, and the two separation devices are both accessible for maintenance from a face wall.

FIELD OF THE ART

The invention relates to an oil-lubricated rotary vane vacuum pump with rotary vane power unit comprising a rotary vane chamber and a rotary vane rotor, and with an oil separating and recycling unit, wherein the separation of oil and gas, which has passed through the rotary vane power unit, is performed in a separating unit, which is preferably formed by a filter element and/or a gravity and/or impact separator and/or a fine separator, preferably together with an oil foam degradation unit and/or with an oil cooler, wherein one or more monitoring and/or maintenance units are provided for the said units and the oil separating and recycling unit is accommodated in an oil separating and recycling housing, with sidewalls, a bottom wall, a ceiling wall and face walls, wherein the sidewalls extend transversely to a rotation plane of the rotary vane rotor and define a longitudinal extension of the oil separating and recycling housing.

STATE OF THE ART

Oil-lubricated rotary vane vacuum pumps of the kind discussed here are known. These normally consist of a rotary vane blower with a rotary vane housing forming a rotary vane chamber, which rotary vane chamber is configured as a cylindrical bore. The rotary vane rotor is normally cylinder-shaped, with slides which are arranged in slots of the rotor. The slots in the rotor may be strictly radially aligned with regard to a cross-section through the rotor or extending at an acute angle to a radial. Mounting of the rotor according to the state of the art is preferably given in the vicinity of the lateral covers terminating the rotary vane housing at either end.

When the vacuum pump is in operation the rotor rotates radially offset relative to the centre axis of the rotary vane housing. This results in closed chambers separated by the essentially radially movably arranged slides, the size of which changes during a revolution of the rotor. From the changes in size differences in pressure result between individual chambers and thus between the inlet side and the outlet side of the pump.

With oil-lubricated rotary vane vacuum pumps oil is introduced into the rotary vane housing. Due to the oil gaps between the different components get blocked. This also obstructs the gas exchange between the adjusting chambers between the slides. In this way higher vacuums are achieved in operation than with so-called dry-running rotary vane vacuum pumps.

Depending on the design the oil together with the conveyed gas is conveyed from the last chamber into the outlet. In addition, due to the compression enthalpy in the system, the oil in the system is heated. Also, the oil as a result of coming into contact with the conveying medium, can become contaminated or can change as a result of possible chemical reactions. The consequence of this is a preferred recycling of the oil after it has left the blower area. In this respect it is known to arrange for the oil to circulate in a cycle through the appliance.

Further it is known to essentially perform the recycling process in three part processes. As such separation of the oil and gas is initially performed in several stages, as required. Coarse separation of large oil drops through a respective filter element may be provided as well as alternatively or in combination therewith, a gravity and/or impact separation by redirecting the gas and oil mixture and alternatively or in combination therewith, by slowing the flow. To separate the oil and gas a fine separation may further be provided, wherein the gas current is for example guided through a special filter mat. In a further part process degradation of the oil foam may be provided. Air bubbles enclosed in the oil can get into the rotary vane chamber in the form of foam and disadvantageously affect the function of the pump.

One or more monitoring and/or maintenance units may be provided, for example an electrical oil level sensor and/or oil level sight glass and/or an oil temperature monitor.

Moreover it is known to house the oil separating and recycling unit in an oil separating and recycling housing, which is separate from the rotary vane housing, but coupled thereto as required. The sidewalls of such a housing extend transversely to the rotation direction of the rotary vane rotor and thus preferably essentially in axial extension direction of the rotary vane rotor.

SUMMARY OF THE INVENTION

With regard to the described state of the art, the invention deals with the task of further improving a rotary vane vacuum pump of the type discussed and implemented so as to be favourable to handling and/or maintenance and/or manufacturing, in particular as regards oil separation.

One possible solution to the requirement according to a first inventive idea presents itself for an oil-lubricated rotary vane vacuum pump, where the aim is for the gas within the oil separating and recycling housing to flow in succession through two separating devices, both of which are accessible for maintenance from one face wall.

According to the invention (at least) two separating devices for the separation of oil and gas are provided in gas flow direction. This results in an altogether better oil separation. The first separating device when viewed in flow direction may be a fine separating device, the second separating device in flow direction may be a post-separating device for separating fine to finest oil particles from the gas current.

Both separating devices are arranged within the oil separating and recycling housing. Any interfaces on the housing for connecting an external, additionally assignable separating device are not necessary. Such interfaces as well as lines leading out of them, for example hoses to an external separating device, represent potential risks to the operation.

Due to the joint arrangement of both separating devices within the same oil separating and recycling housing an internal earthing of both components, moreover together with any further components received in this housing, is possible. Static discharges and flying sparks can be safely avoided in this way.

The sequentially connected separating devices in flow direction offer a step-like separation.

The preferred accessibility of both separating devices via a face wall of the oil separating and recycling housing has proven to be favourable to handling, in particular with a preferred one-behind-the-other arrangement of the separating devices, wherein when viewed from the face wall the one separating device behind the separating device initially visible from the face wall is at least partially arranged to be hidden.

Further features of the invention will now, as well as in the description of the figures, be explained in terms of their preferred assignment to the subject of claim 1 or in relation to features in further claims. But they may also be of importance in terms of an assignment to merely individual features of claim 1 or to the respective further claim or independently, respectively.

In one possible design the two separating devices may be singly insertable and removable. Insertion/removal, as preferred, may be performed in a specified order. Moreover removal of one separating device may be dependent on the removal of the other separating device.

In one alternative design the two separating devices may be connected to each other for their combined joined insertion and removal. Such a connection may be undone after a removal, for example for replacing only one of the separating devices.

Insertion and removal may refer to the entire separating unit (first and/or second separating device). In this respect removal or insertion of only filter elements of the separating devices is also possible. These filter elements may also be accessible via the one face wall. Also this arrangement may be chosen such that one separating device is completely removable from the housing for maintenance or replacement, whilst with the second separating device preferably only the associated filter element is removable as part of the usual maintenance.

The gas path between the first separating device viewed in gas flow direction and the second separating device viewed in gas flow direction may be designed valvefree, as is preferred. This, as is preferable, results in a transition without pressure loss from the first separating device into the second separating device, wherein in a preferred design the line section defining the gas path between the separating devices is given through the oil separating and recycling housing.

The length of the gas path in gas flow direction between the first separating device viewed in gas flow direction may correspond to a diameter dimension or less of the first separating device. The length of the gas path can tend towards zero, for a direct (linear) sequential arrangement of the two separating devices. The diameter dimension of the first separating device preferably refers to a maximum extension dimension in a cross-section transversely to the longitudinal extension/transversely to the gas flow direction within the separating device, here with regard to the filter material serving the oil separation.

With a preferred circular-cylindrical design of the first separating device/its separating filter, the maximum extension dimension in cross-section is the diameter dimension. For an exemplary cross-section of the filter material the previously mentioned diameter dimension corresponds for example to the longest extension dimension in the cross-section area.

The separating devices are fine separating or air/oil separating elements, further so-called oil mist separators, wherein the in-gas-flow-direction downstream second separating device comprises a higher degree of separation compared to the first separating device and thus a higher particle filter class.

Also, as preferred, the one or more monitoring and/or maintenance units may be arranged in only three cover parts, which are attached to the two face walls of the oil separating and recycling housing, wherein the oil separating and recycling housing may, by the way, be formed with sidewalls, a bottom wall, a ceiling wall and face walls for a monitoring and/or maintenance unit.

The cover parts may be assigned to the face walls of the oil separating and recycling housing. As such one face wall may be configured for example as the rear side cover, and one service cover may be assigned to a front face wall common used in operation. In addition the service cover may have a maintenance cover arranged on it, which is removable for maintenance purposes.

Moreover the monitoring and/or maintenance units, further preferably all monitoring and/or maintenance units relevant to normal operation of the vacuum pump, may be provided in or on the three cover parts. Furthermore, frequently used monitoring and/or maintenance units may be provided in the service cover or in the maintenance cover which can be arranged on the service cover/are accessible via the same.

Essential functions are preferably situated within the area of the three cover parts/can be performed within the area of these. In particular these functions are oil filling and/or oil checking and/or oil monitoring and/or oil draining and/or fastening of one or both separating devices and/or providing access for the maintenance of the one or both separating devices and/or fastening of a float device and/or providing access to the float device and/or providing space for separated oil and/or providing a return for collected oil and/or a receptacle for the maintenance cover and/or dividing the oil separating and recycling housing into an upper and lower space and/or connecting an oil heater and/or connecting a water cooler and/or connecting a filter and/or connecting elements downstream of the vacuum pump and/or directing discharged air into a defined direction.

The oil separating and recycling housing as such without the above-mentioned cover parts is preferably without a relevant function, at least as regards the user interface. V Thus this housing may be constructed in a simple manner. As such the ceiling wall and the bottom wall in particular, further preferably also at least one external sidewall may be designed without any preparation for arranging relevant devices.

The float device is generally a control for the through-flow from the upper into the lower chamber. It is influenced in particular by an oil level developing in the upper chamber. Exceeding a certain predefined oil level shall be avoided. In the following, for simplicity's sake, this device is always called float device. The common return of the separated oil of both separating devices into the oil circuit is effected via this float device.

In a further design the one or more monitoring and/or maintenance units may be arranged on a removable maintenance cover of the oil separating and recycling unit, wherein when the maintenance cover is removed, one or both separating devices and/or a float device are accessible for maintenance.

The one or more monitoring and/or maintenance units may be assigned to a housing area of the oil separating and recycling unit, in which area a removable maintenance cover is formed. The monitoring and/or maintenance units may be directly arranged/formed on the maintenance cover, or as required in the direct vicinity of the maintenance cover in the surrounding housing area. This leads to a reduction in the space required for the rotary vane vacuum pump in the installation and usage area. By removing the maintenance cover from the oil separating and recycling housing access to components of the oil separating and recycling unit is made possible, in particular access to one or both separating devices and/or a float device. Such a float device may be required in order to allow the gas current to flow selectively through the one or more separating units as a consequence of differences in pressure in the area of the vacuum pump. This involves separated oil being collected in a cavity preferably formed in a service cover forming a face wall of the oil separating and recycling housing. A hollow body is arranged in the cavity which may also be called an oil-collecting chamber, the hollow body being connected to a joint, preferably a rotary joint and a seal. The seal blocks the return of the oil. As the oil level rises the hollow body starts to float, and the joint causes the seal to be raised, which frees an opening for the return of the oil.

The maintenance cover may be configured and arranged in such a way that the oil behind it in the oil separating and recycling housing cannot escape on removal of the maintenance cover, wherein the maintenance cover may be arranged in the area of one face wall of the oil separating and recycling housing. Or the maintenance cover may be arranged on a service cover assigned to a face wall of the oil separating and recycling housing.

As regards its longitudinal extension, the oil separating and recycling housing may be comprised of a profile with a consistent cross-section. Such a profile may be an extruded section profile. This makes it possible to produce the housing of the oil separating and recycling plant in a particularly economic manner. The contour is preferably identical at each point of the longitudinal axis of the housing part. With regard to an extruded section profile an aluminum-wrought alloy is pressed through a two-dimensional die, so that an elongated profile is produced, which can be cut to the preferred length. This allows producing such a housing with dimensionally stable contours over the entire length.

The external surfaces may be formed optically clean and even. Further working steps, in particular surface treatment steps, may be omitted, in particular with a manufacture from an extruded section profile. Moreover, as a result of the proposed construction of the housing, the surface of the same may be presented as a decorative element.

The consistent cross-section profile, preferably the extruded section profile, offers the possibility of modifying the volume of the oil separating and recycling unit and to adapt it to the needs of the application.

Insofar as reference is made above and below to an extruded section profile, it is, also in general terms, always to be understood as a consistent section profile.

It may further be provided that the maintenance cover forms part of a face wall of the oil separating and recycling housing or the face wall in total. In the operating position of the vacuum pump the face wall may be aligned with/face an operator or control person. In a preferred design the maintenance cover covers an opening provided in the face wall of the housing, through which for example the one or both separating devices and/or the float device are accessible for maintenance. As such the maintenance cover as regards its cover surface, may be of a size, which corresponds to 0.25 to 0.5 times the outward-pointing end surface of the face wall.

The separating devices, as regards the through-flow direction, can be arranged in longitudinal direction of the oil separating and recycling unit. Further, the separating devices, as regards the through-flow direction, are preferably arranged in longitudinal direction of the extruded section profile of the housing.

Preferably the maintenance cover is arranged as an extension of at least one of the separating devices in the area of the face wall. A longitudinal centre axis of the separating device can, as an extension of the same, pass through the maintenance cover in the area of its broadside surfaces.

After removal of the maintenance cover the filter element, preferably in form of a special filter mat, can be removed from the separating device configured as a fine separating device. It can then be simply replaced for example by a new filter element.

A sidewall is provided between the rotary vane power unit and the oil separating and recycling unit. This may be the sidewall of the oil separating and recycling housing. The sidewall may comprise a through-opening, through which compressed gas with a percentage of oil from the rotary vane power unit can enter into the oil separating and recycling unit.

The gas entering with a percentage of oil can, in a first portion of the oil separating and recycling unit, flow in counter-direction to a second portion, in which second portion oil separation, for example fine separation, takes place. The flow direction, as preferred from now on, may be in longitudinal extension of the oil separating and recycling housing, and thus as further preferred, in longitudinal extension of the extruded section profile. This is an essential flow direction from one end region of the housing along its longitudinal extension to the other end region of the housing, wherein deviations may be provided from a strictly linear flow direction within this flow from one end to the other end of the housing.

Below the through-opening a housing portion may follow formed as a flow path, into which oil flows which has been separated from the gas as a result of gravity and/or centrifugal forces. This housing portion may serve as an oil sump, may thus be configured as a kind of oil trough. A first separation of gas and oil is preferably effected via a gravity and/or centrifugal force separation.

In order to permit an oil change, possibly also a connection of an oil cooling circuit, the housing portion has at least one oil outlet opening. This may, as is preferred, be formed in the vertically lowest area of the housing portion, when the vacuum pump is in the installation and operating position. Further preferably the oil outlet opening is closable.

The oil outlet opening may also be accessible from an face wall of the oil separating and recycling housing. In a preferred design the oil outlet opening is assigned to the face wall, on which the maintenance cover is also arranged.

In order to, in particular, separate particles out of the oil separated from the gas, an oil filter may further be provided in the housing portion or assigned to the same, through which the oil present in the housing portion can be directed. The oil filter may preferably be an exchangeable oil filter.

The oil directed through the oil filter can preferably be fed into the rotary vane chamber. To this end a pump may be provided, which sucks the oil collecting in the housing portion in through the oil filter and conveys it into the rotary vane chamber of the rotary vane power unit. A design without pump is preferred, and oil delivery is effected by making use of the pressure difference between the oil collecting chamber and the working space of the vacuum pump.

A filter mat may be provided in the fine separating device (first separating device). This filter mat is preferably replaceable, wherein in a preferred design, such a replacement is performed from the one face wall comprising the maintenance cover, following removal of the maintenance cover.

The filter mat may be tube-shaped with an inner flow path for the gas/oil mixture. Oil separated in the fine separating device flows, in a preferred design, via the post-separator (second separating device) and via the float device into the housing portion comprising the oil collecting chamber.

The flow resistance of the filter elements (filter mat) in the separating devices results in a pressure difference in front of and behind the fine separating device. This may be up to 400 mbar depending on the volume current currently delivered by the pump.

The float device may be formed directly on the maintenance cover or preferably be accessible after removal of the maintenance cover. This also offers an improvement in maintenance.

Also an oil level indication may be provided on the face wall, in or on the maintenance cover, as required. The oil level of the vacuum pump can be read therefrom. This may be a conventional sight glass or alternatively an analogue or digital measurement value display.

Further, an overpressure valve or a bursting disc may be arranged, as required, on the face wall or in the maintenance cover. Such an overpressure valve or bursting disc serves as a safeguard against a sudden overpressure in the appliance. In case a bursting disc is arranged in the maintenance cover, a safe operating state may be reinstated after an event in a simple manner regarding handling, for example by, in total, changing the maintenance cover.

In a further design a temperature monitoring element may be arranged in the face wall, as required, in the maintenance cover or associated with the maintenance cover. This in particular serves monitoring of the oil temperature.

The gas separated out of the oil may in a possible design exit through the face wall, further for example through the maintenance cover. To this end the face wall, in particular the maintenance cover, comprises an appropriate outlet opening.

In one possible design the maintenance cover comprises a gas outlet connection. This may be arranged for connection to a sound absorber or a continuation element. As such the gas outlet connection, in a first design of the maintenance cover, may be provided with a thread. This may be used for connection to outlet piping. The thread may also be used for connection to a bursting disc. As required, the bursting disc may also be arranged and fastened in the outlet piping. If required a pipe line, a sound absorber or other gas conducting elements may be connected. By changing the maintenance cover an appropriately equipped maintenance cover may be arranged if the appliance is situated at the place of use.

In a further design the gas outlet connection may be provided with a possibly removable redirecting cap, in which the exiting gas is redirected by at least 60° with regard to a given outlet direction. Preferably redirection is chosen such that the exiting gas flows out in downward-direction. As a result noise pollution in operation of the vacuum pump is reduced because the sound is directed in a direction towards the bottom. The gas outlet connection may also be arranged so as to be rotatable on the maintenance cover, so that for example redirection to the side or towards the top is possible.

The oil separating and recycling housing may comprise integrally formed chambering comprising an upper and a lower chamber with, in the installation state as regards gravity, an upper and a lower chamber, wherein in longitudinal direction of the oil separating and recycling housing a face wall may be connected at the front and at the back. As part of the preferred manufacture of the housing the integral forming of chambers may be produced from an extruded section profile. The upper chamber, in the preferred design, serves, in particular, to receive the separating devices, whilst the chamber which is the lower chamber when the vacuum pump is in operation, constitutes the previously described housing portion. The face walls to be connected each form an end-side termination of the oil separating and recycling housing. One of the face walls may comprise an opening covered by the previously described maintenance cover.

At least one face wall preferably constitutes a connection of the chambers. With a preferably counter-directed flow within the chambers at least one face wall may constitute gas-redirection regions.

The through-opening from the rotary vane power unit/from the rotary vane chamber to the oil separating and recycling unit leads, in a preferred design, into the lower chamber of the oil separating and recycling housing. This through-opening is joined, when viewed in flow direction, to the gravity and/or impact separator.

Further the lower chamber, in a preferred design constitutes an oil collecting container.

One or more cooling lines preferably integrated in the extruded section profile may be provided assigned to the oil collecting container. Inlets and outlets for cooling the oil by means of an external cooler may also be provided in the area of the oil collecting container.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will now be explained in detail by way of the attached drawing, which merely represents an exemplary embodiment and in which

FIG. 1 shows an oil-lubricated rotary vane vacuum pump in a perspective view;

FIG. 2 shows a respective top view;

FIG. 3 shows the vacuum pump in a side view, looking at a face wall with the maintenance cover;

FIG. 4 shows the section as per line IV-IV in FIG. 3;

FIG. 5 shows the section as per line V-V in FIG. 2;

FIG. 6 shows a perspective detail view of the oil separating and recycling housing;

FIG. 7 shows a perspective detail view of the face wall with associated maintenance cover and a gas outlet connection attachable to the maintenance cover;

FIG. 8 shows a perspective detail view of the maintenance cover, looking at the inner surface when in use;

FIG. 9 shows a sectional view of the oil separating and recycling housing;

FIG. 10 shows the section as per line X-X in FIG. 2.

DESCRIPTION OF THE EMBODIMENTS

What is shown and described, initially with reference to FIG. 1, is an oil-lubricated rotary vane vacuum pump 1 with a rotary vane power unit and an oil separating and recycling unit 3.

The rotary vane power unit 2 comprises a power unit housing, in which a rotary vane chamber 5 with a rotary vane rotor 6 are arranged. The power unit housing is covered by a hood 4 and side covers 11 and 12 arranged respectively, at the end with reference to a longitudinal axis.

The rotary vane chamber 5 is configured as a cylindrical bore in the power unit housing. The rotary vane chamber 5 comprises a longitudinal extension, which orients itself on the bore axis of the rotary vane chamber 5.

The cylindrically shaped rotary vane rotor 6 is eccentrically arranged relative to the rotary vane chamber 5. Correspondingly, the rotor axis x extends in parallel, but offset to the chamber axis.

The rotary vane rotor 6 comprises several, in the exemplary embodiment three slides 7. These are arranged in a slidably movable manner in approximately radially aligned slots 8 of the rotor 6 when viewed in cross-section. Due to the rotation of the rotary vane rotor 6 as a result of the centrifugal force the slides 7 are pressed against the wall bounding the rotary vane chamber 5.

In operation of the vacuum pump 1 the rotary vane rotor 6 rotates radially offset to the centre axis of the rotary vane chamber 5, this in consequence of being driven via a motor rotatingly impacting the rotor shaft, in particular electric motor 9. This results in closed chambers 10, separated by the radially movably arranged slides 7, wherein the size of the chambers changes during a revolution of the rotary vane rotor 6.

The rotary vane chamber 5 is closed on either side with regard to its longitudinal axis by rotary vane covers 46 and 47 (see FIG. 10).

Outside the power unit housing, for example associated with the side cover 12, the electric motor 9 is preferably fastened to the power housing. The shaft of the rotary vane rotor 6 may extend through the respective side cover 12 in order to permit torque-proof engagement of the electromotor 9.

Changes in the size of chambers 10, when the vacuum pump is in operation results in pressure differences between the individual chambers 10 and thus between the inlet side and the outlet side of the thus formed blower.

The drive via the electric motor 9 may be arranged directly on the rotor shaft or, as further preferred, via a coupling.

Oil-lubricated rotary vane power units are characterized in that with these oil is introduced into the rotary vane chamber 5. This oil leads to gaps between the different components becoming blocked, in particular between the slides 7 and the wall of the rotary vane chamber 5. The exchange of gas between the different chambers 10 is thus obstructed. In this way, during operation, higher vacuums are achieved than is possible with dry-running rotary vane pumps.

Depending on the construction the oil together with the conveyed gas is conveyed out of the last chamber 10 of the rotary vane power unit 2. In addition the oil is heated due to the compression enthalpy in the system. Since the oil comes into contact with the conveying medium (gas), this may contaminate or may change due to possible chemical reactions.

The oil flows in a cycle process through the vacuum pump 1. This means that after it has left the rotary vane power unit 2, it must be recycled. The oil separating and recycling unit 3 serves this purpose.

The unit 3 is connected to the rotary vane power unit 2 so that a unit is formed consisting of rotary vane power unit 2, oil separating and recycling unit 3 and electric motor 9.

The oil separating and recycling unit 3 to begin with comprises an oil separating and recycling housing 13, with sidewalls 14, 15, a bottom wall 16, a ceiling wall 17 and face walls 18, 19.

The face walls 18 and 19, viewed in longitudinal extension of the housing 13, which longitudinal extension corresponds to the longitudinal extension of the rotary vane power unit 2, are arranged at either end of the housing integrally formed by the sidewalls 14 and 15, the bottom wall 16 and the ceiling wall 17, in particular are connected by screws to the housing. The face wall 18 is preferably formed by a service cover and the face wall 19 is formed by a rear side cover.

The housing 13, as regards its longitudinal extension, may consist of an extruded section profile 20, in particular of an aluminum extruded section profile. The oil separating and recycling housing 13 comprises an essentially consistent cross-section over its length, when viewed along its longitudinal extension while maintaining a dimensionally stable contour. Moreover during manufacture of the housing 13 by means of an extrusion process the external surfaces are designed optically uniform and clean so that surface treatment steps for optical improvement of the surface may be omitted. Provision need merely be made for necessary machining steps such as breakthroughs in the sidewalls and/or bottom wall and/or ceiling wall.

Also manufacture of the housing 13 by means of an extrusion process may be utilized such that apart from the surface the shape of the housing may be configured such that in the end this defines the design characterizing element.

The sidewalls 14 and 15 extend transversely to a rotation plane of the rotary vane rotor 6, wherein in the embodiment shown the sidewall 14 also represents the fastening plane for fastening the oil separating and recycling housing 13 in the power unit housing.

The face wall 18 arranged at the end finishes flush with the adjacent side cover 11 on the external side of the wall in one possible embodiment, and the same preferably goes for the ceiling wall 17 and the bottom wall 16 with the adjoining adjacent wall portions of the power unit housing. This results in a compact and optically pleasing unit.

The external surface of the sidewall 15 facing away from the rotary vane power unit 2 and thus facing the outside is shaped in a corrugated manner (see FIG. 9 in particular) as regards a cross-section in the rotation plane of the rotary vane rotor 6. When viewed in cross-section across the extension length of the sidewall 15, this results in uniform rounded elevations, which are connected with each other via valleys. This results in an enlargement of the surface in the area of the sidewall 15 and thus in an improvement of the heat dissipation in operation of the vacuum pump 1.

The corrugated surface in a preferred design continues in the facing surface areas of the face walls 18 and 19.

The oil separating and recycling housing 13 comprises a preferably integrally formed chambering. With regard to an installation state, as depicted, this results, as regards gravity, in a lower chamber 21 and an upper chamber 22. The division of the chambers 21 and 22 is achieved by a separating bar 23 extending transversely to the sidewalls 14 and 15 with regard to a cross-section as per FIG. 9.

In operation of the vacuum pump 1, separation of oil and gas takes place in particular in the oil separating and recycling unit.

To this end to start with a gravity and/or impact separator 24 and a downstream (in gas flow direction) two-stage separator are provided, which is composed of a first separating device T₁ in form of a fine separating device 25 and a downstream second separating device T₂ in the form of a post-separating device 43.

The oil/gas mixture enters from the rotary vane power unit 2 via through-opening 26 in the area of the sidewall 14 into the oil separating and recycling unit 3.

With the entry into the unit 3 a coarse separation of large oil drops through the gravity and/or impact separator 24 takes preferably place initially as a consequence of redirection of the gas/oil mixture and a slow-down of the flow.

The entry of the oil/gas mixture into the unit 3 takes place in consequence of a respective arrangement of the through-opening 26 in the area of the lower chamber 21, in which accordingly a separating device T₃ may be arranged, such as in the form of a gravity and/or impact separator 24.

The housing portion 27 resulting below the through-opening 26 in the area of the lower chamber 21 serves like a kind of oil trough in which an oil sump collects. Thus an oil collecting container is formed in the lower chamber 21.

Further, the lower chamber 21 forms a flow path with a flow a oriented in longitudinal direction of the housing. This flow a is directed in direction of the rear face wall 19.

In order to avoid that the gas flow stirs up the oil collecting in the oil sump, the area of the oil trough is covered by a pulled-in filter sheet 44.

The inside of the face wall 19 is configured for redirecting the flow from the lower chamber 21 into the upper chamber 22, in which the flow path formed in the upper chamber 22 permits a flow b in the opposite direction to flow a in the lower chamber 21.

The separating devices T₁ and T₂ are provided in the upper chamber 22 in a linear one-behind-the-other arrangement.

The fine separating device 25 (separating device T₁) comprises a tube-shaped filter mat 42, the tube axis of which is preferably pointing in the same direction as the rotor axis x of the rotary vane rotor 6. Further the fine separating device 25 is essentially arranged oriented in longitudinal direction of the oil separating and recycling housing 13.

In gas flow direction b downstream of the fine separating device 25 a post-separating device 43 is provided in the upper chamber 22. The gas exiting from the fine separating device 25 is, of necessity, guided through the post-separating device 43. The length c of the gas path between the first separating device T₁ (fine separating device 25) viewed in gas flow direction b and the second separating device T₂ (post-separating device 43) viewed in gas flow direction b approximately corresponds to a fourth to third of the diameter dimension of the first separating device T₁ (with regard to the largest cross-section extension dimension of the filter-effective element).

The oil-gas mixture redirected from the lower chamber 21 into the upper chamber 22 is selectively and successively guided through the two separating devices T₁ and T₂, wherein a pressure difference results in front of the first separating device T₁ and behind the second separating device T₂, which depending on the delivery pressure of the rotary vane power unit 2 may be up to 400 mbar.

Furthermore an oil foam degradation device may be provided in the oil separating and recycling unit 3.

Moreover an oil filter 28 is provided. This may be arranged assigned to the floor area of the oil separating and recycling housing 13, further preferably to the rear face wall 19. The oil present in the oil sump is sucked-in through the oil filter 28 and in particular freed from solid particles.

Utilizing the pressure difference between the lower chamber 21 and the chamber 10 in the rotary vane power unit 2 the oil filtered in the oil filter 28 is conveyed via the suction line 29 into the rotary vane power unit 2.

By means of an external cooler not shown cooling of the in particular filtered oil can be performed. To this end respective inlets and outlets are provided in the area of the lower chamber 21.

Cooling paths can also be provided in the profile of the housing 13, for example in the area of the bottom wall 16 and/or the sidewalls 15 (assigned to the lower chamber 21).

The face wall 18 preferably facing an operator when in use leaves a passage on the inside of the wall for connection of the upper chamber 22 to the lower chamber 21, which passage is formed by a float device 30. Oil separated at the two separating devices T₁ and T₂ is directed back into the reservoir in the area of the lower chamber 21, this through the float device 30. Due to the above-described pressure difference in front of and behind the separating devices T₁ and T₂ this prevents gas entering through the through-opening 26 into the lower chamber 21 from flowing in a bypass-like manner directly to the gas outlet 31.

In addition an oil bath heater may be provided in order to heat the oil prior to the start of the vacuum pump 1.

Moreover additional water cooling may be provided.

The oil bath heater and/or water cooling may be arranged on the face wall 19.

In the face wall 18 facing away from the electric motor 9 and forming a front side when in operation a window-like opening 32 extending at least approximately over the entire cross-section surface of the upper chamber 22 and assigned to the upper chamber 22 may be provided. This window opening is closed by a maintenance cover 33 when the vacuum pump 1 is in operation. The maintenance cover 33 may be screwed to the face wall 18, preferably via a seal.

The gas outlet 31 is provided in the maintenance cover 33. To this end the maintenance cover comprises a through-opening 34, to which a gas outlet connection 35 can be connected on the outside of the wall of the maintenance cover 33.

The gas outlet connection 35 may be configured as a removable redirecting cap 36, in which the exiting gas, as regards its alignment given by the gas outlet connection, the alignment being essentially the same as the flow b in the upper chamber 22, is directed by at least 60°, preferably up to 90°, in a downward direction towards the plane given by the bottom wall 16. As a result the sound is directed towards the bottom, which leads to a reduction in noise pollution.

Preferably the gas outlet connection 35 is rotatably arranged on the maintenance cover 33, so that the exhaust air can be selectively directed for example also to the side or towards the top.

The redirecting cap 36 can be replaced, for example, by a gas outlet connection for connection to a sound absorber or a continuation element.

Moreover a maintenance cover 33 with redirecting cap 36 may be replaced by a maintenance cover 33 for connection for example to external piping.

The oil separating and recycling unit 3 comprises a number of monitoring and/or maintenance units 37. As such an oil level indication 38 for determining the oil quantity may be provided in the face wall 18, assigned to the lower chamber 21. The oil level indication 38 may be formed by an oil sight glass and/or an electrical oil level sensor.

Also a possible oil temperature indication may be arranged in the area of the face wall 18.

Further both the flow and the return for changing the oil in the oil separating and recycling unit 3 may be provided in the face wall 18. To this end an oil outlet opening 39 and a fill-in connection 40 are provided in the face wall 18 in one design.

After removal of the maintenance cover 33 assigned to the face wall 18 both separating devices T₁ and T₂ and the float device 30 are accessible for maintenance and, as required, replacement from the operating side of the vacuum pump 1.

As such following removal of the face wall 18 the separating device T₂ (post-separating device 43) is initially exposed. This can then be removed from the upper chamber 22. The post-separating device 43 may be fastened for example on a carriage-type frame 45. The post-separating device 43 in one design can be removed from the upper chamber 22 together with the frame 45, whereafter the filter mat 42 of the fine separating device 25 is also free for removal/the filter mat 42 can be accessed for maintenance purposes.

The gas path between the two separating devices T₁ and T₂ is designed without valves, and in the depicted embodiment, with regard to solely one cross-section, is surrounded by the material of the oil separating and recycling housing 13 in the area of the upper chamber 22.

The post-separating device 43 may comprise a filter mat or the like, which is essentially permeable in flow direction b.

In addition an overpressure valve may be arranged in the maintenance cover 33.

The overpressure valve serves as a safeguard against a sudden overpressure in the oil separating and recycling unit 3; is thus preferably part of the monitoring unit.

The face walls 18 and 19 as well as the maintenance cover 33 are, as cover parts A, B and C, assigned directly or indirectly (cover part C/maintenance cover 33) to the oil separating and recycling housing 31.

As a consequence of the above-described arrangement of the monitoring and/or maintenance units 37 as well as of the design of the over parts A, B and C, preferably all interfaces are accommodated in an easily accessible manner in the area of the face walls 18, 19, so that the space requirement for the appliance is reduced, thereby increasing ease of maintenance and simplifying manufacture of the oil separating and recycling housing.

The above statements serve to explain the inventions covered in total by the application, wherein the inventions further develop the state of the art, at least due to the following feature combinations, also on their own, respectively, i.e.

A rotary vane vacuum pump 1, which is characterized in that the gas within the oil separating and recycling housing 13 flows in succession through two separating devices T₁, T₂, both of which are accessible for maintenance from a face wall 18.

A rotary vane vacuum pump 1, which is characterized in that both separating devices T₁, T₂ are singly insertable and removable.

A rotary vane vacuum pump 1, which is characterized in that both separating devices T₁, T₂ are connected to each other, combined for joint insertion and removal.

A rotary vane vacuum pump 1, which is characterized in that a gas path is formed without valves between the separating device T₁ which is first in gas flow direction b and the separating device T₂, which is second in gas flow direction b.

An oil-lubricated rotary vane vacuum pump 1, which is characterized in that the length c of the gas path between the separating device T₁ which is first in air flow direction and the separating device T₂ which is second in air flow direction b corresponds to a diameter dimension or less, of the first separating device T₁.

List of reference symbols 1 vacuum pump 2 rotary vane power unit 3 oil separating and re- cycling unit 4 hood 5 rotary vane chamber 6 rotary vane rotor 7 slide 8 slot 9 electric motor 10 chamber 11 side cover 12 side cover 13 oil separating and re- cycling housing 14 sidewall 15 sidewall 16 bottom wall 17 ceiling wall 18 face wall 19 face wall 20 extruded section profile 21 lower chamber 22 upper chamber 23 separating bar 24 gravity and/or impact separator 25 fine separating device 26 through opening 27 housing portion 28 oil filter 29 suction line 30 float device 31 gas outlet 32 opening 33 maintenance cover 34 through opening 35 gas outlet connection 36 redirecting cap 37 monitoring and maintenance unit 38 oil filter indication 39 drain opening 40 fill-in connection 42 filter mat 43 post-separating device 44 filter sheet 45 frame 46 rotary vane side cover 47 rotary vane side cover a flow b flow c length x rotor axis A cover part C cover part T₁ separating device T₂ separating device T₃ separating device 

1. An oil-lubricated rotary vane vacuum pump (1) with rotary vane power unit (2), comprising a rotary vane chamber (5) and a rotary vane rotor (6) and with an oil separating and recycling unit (3), wherein a separation of oil and gas, which has passed through the rotary vane power unit (2), is effected in the oil separating and recycling unit (3) by a separating device (T₁, T₂), which is preferably formed by a filter element and/or by a gravity and/or impact separator (24) and/or a fine separator (25), preferably in conjunction with an oil foam degradation unit and/or with an oil cooler and/or with an oil pump, wherein one or more monitoring and/or maintenance units (37) are provided for the said units and the oil separating and recycling unit (3) is accommodated in an oil separating and recycling housing (13) with sidewalls (14, 15), a bottom wall (16), a ceiling wall (17) and face walls (18, 19), wherein the sidewalls (14, 15) extend transversely to a rotation plane of the rotary vane rotor (6) and define a longitudinal extension of the oil separating and recycling housing (13), wherein the gas within the oil separating and recycling housing (13) flows through two separating devices (T₁, T₂), which are both accessible for maintenance from a face wall (18).
 2. The rotary vane vacuum pump according to claim 1, wherein both separating devices (T₁, T₂) are singly insertable and removable.
 3. The rotary vane vacuum pump according to claim 1, wherein both separating devices (T₁, T₂) are connected to each other, combined for joint insertion and removal.
 4. The rotary vane vacuum pump according to claim 1, wherein a gas path is formed without valves between the separating device (T₁), which is first in gas flow direction (b) and the separating device (T₂), which is second in gas flow direction (b).
 5. The rotary vane vacuum pump according to claim 1, wherein the length (c) of the gas path between the separating device (T₁), which is first in gas flow direction (b) and the separating device (T₂), which is second in gas flow direction (b) corresponds to a diameter dimension or less, of the first separating device (T₁).
 6. The rotary vane vacuum pump according to claim 1, wherein a further separating device (T₃) is provided, for example in the form of a gravity and/or impact separator (24). 